Methods for improving uplink (UL) coverage, throughput, and transmission latency are currently being investigated in Release 6 of the Third Generation Partnership Project (3GPP). In order to achieve these goals, the Node-B will take over responsibility of scheduling and assigning uplink resources to WTRUs. The Node-B can make more efficient decisions and manage UL radio resources on a short-term basis better than the RNC, even if the RNC retains coarse overall control.
A new media access control (MAC) function/entity for enhanced uplink (EU) called MAC-e is created in a WTRU and the Node-B to handle the transmission and reception of the E-DCH transmissions. To properly support EU, information such as channel allocations, transmission feedback, (i.e., acknowledge (ACK) or non-acknowledge (NACK)), and other feedback information, (such as power control command or channel quality), must be transmitted to the WTRU via a DL EU signaling channel efficiently and reliably.
Power control on the shared DL EU signaling channel is essential to support proper operation of the DL EU signaling channel. Power control reduces overall interference and therefore results in more efficient use of radio resources.